<template>
  <div class="spec-preview">
    <!-- 可以看出，报红的原因是skuImageList可能是一个空数组的第0项是undefined的.imgUrl会报错，可以让其为空对象，便不会报错 -->
    <img :src="objImg.imgUrl" />
    <div class="event" @mousemove="handler"></div>
    <div class="big">
      <img :src="(objImg||{}).imgUrl" ref="big"/>
    </div>
    <div class="mask" ref="mask"></div>
  </div>
</template>
<script>
  export default {
    name: "Zoom",
    props:["skuImageList"],
    data() {
      return {
        showPic:0
      }
    },
    computed:{
      objImg(){
        return this.skuImageList[this.showPic]||{}
      }
    },
    mounted() {
      this.$bus.$on("changePic",(index)=>{
        this.showPic=index;
      })
    },
    methods: {
      //放大器效果
     handler(event){
      //  console.log(event);
       let mask=this.$refs.mask;
       let big=this.$refs.big;
       let left=event.offsetX-mask.offsetWidth/2;
       let top=event.offsetY-mask.offsetHeight/2;
       if (left<0) {
         left=0;
       };
       if (left>mask.offsetWidth) {
         left=mask.offsetWidth;
       };
       if (top<0) {
         top=0;
       };
       if (top>mask.offsetHeight) {
         top=mask.offsetHeight;
       };
       mask.style.left=left+"px";
       mask.style.top=top+"px";
       big.style.left=-2*left+"px";
       big.style.top=-2*top+"px";
     }
    },
  }
</script>
<style lang="less">
  .spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;
    img {
      width: 100%;
      height: 100%;
    }

    .event {
      width: 100%;
      height: 100%;
      position: absolute;
      top: 0;
      left: 0;
      z-index: 998;
    }

    .mask {
      width: 50%;
      height: 50%;
      background-color: rgba(0, 255, 0, 0.3);
      position: absolute;
      left: 0;
      top: 0;
      display: none;
    }

    .big {
      width: 100%;
      height: 100%;
      position: absolute;
      top: -1px;
      left: 100%;
      border: 1px solid #aaa;
      overflow: hidden;
      z-index: 998;
      display: none;
      background: white;

      img {
        width: 200%;
        max-width: 200%;
        height: 200%;
        position: absolute;
        left: 0;
        top: 0;
      }
    }

    .event:hover~.mask,
    .event:hover~.big {
      display: block;
    }
  }
</style>